This invention relates to the hydrometallurgical treatment of metal ores or concentrates. In particular, it relates to the extraction of copper from sulphide ores or other concentrates in the presence of halogen ions, such as chloride ions.
The hydrometallurgical treatment of sulphide concentrates whereby the concentrate is subjected to pressure oxidation in the presence of chloride ions is known. See for example U.S. Pat. No. 4,039,406; 5,645,708; and 5,650,057.
The purpose of the present invention is to provide an improved process for the extraction of metals from sulphide ores.
According to the invention there is provided a process for the extraction of copper from a sulphide copper ore or concentrate, comprising the steps of subjecting the ore or concentrate to pressure oxidation in the presence of oxygen and an acidic solution containing halide and sulphate ions to obtain a resulting pressure oxidation slurry, subjecting the slurry to a liquid/solid separation step to obtain a resulting pressure oxidation filtrate and a solid residue containing an insoluble basic copper sulphate salt; leaching the basic copper sulphate salt produced by the pressure oxidation with an acidic sulphate solution in a second leaching to dissolve the basic copper salt to produce a leach liquor containing copper sulphate in solution and a resulting solid residue; separating the leach liquor from the solid residue; subjecting the leach liquor to a solvent extraction process to produce copper concentrate solution and a copper depleted raffinate; recycling at least a portion of the raffinate to the pressure oxidation; and wherein the raffinate is subjected to evaporation to remove water therefrom prior to the recycle thereof; and wherein the evaporation is effected by means of a direct-fired evaporation process comprising the submerged combustion of a fuel in the raffinate being recycled.
The term xe2x80x9cconcentratexe2x80x9d in this specification refers to any material in which the metal value content has been increased to a higher percentage by weight as compared with the naturally occurring ore and includes man made artificial sulphide ore, such as matte, and metal values precipitated as solids such as hydroxides and sulphides.
Further objects and advantages of the invention will become apparent from the description of preferred embodiments of the invention below.